The underlying integer values of each value in the enumeration are deliberately chosen to match the Collaborative Application Markup Language (CAML) Type ID number of the list type. (This ID is the value of the Type attribute of the ListTemplate Element (List Template) and the List Element (List).)

Keep in mind that Microsoft Corporation products that are built on SharePoint Foundation, such as Microsoft SharePoint Server, can and do define additional list types. Also, Microsoft SharePoint Foundation farms where your solution is deployed may have custom list types created, for example, by adding a CAML ListTemplate Element (List Template) to a Feature or to the ONET.xml file of a custom site definition configuration. (Such custom list types should have ID values above 10000 to ensure that they do not conflict with numbers that will be used by Microsoft in future versions of SharePoint Foundation.) Since these list types are not have corresponding values in this enumeration, you should consider not using this enumeration as a parameter value in your custom methods. Consider, instead, using String or Int32 parameters that take the list type ID as string or integer.